Which company is leading in cloud-based infrastructure services? According to new data, although Amazon Web Services () is still the biggest, Microsoft and IBM are growing the fastest.

The Synergy Research Group has released second quarter data that shows Amazon is no longer bigger than its nearest four competitors combined. The research firm estimates that quarterly revenues from infrastructure-as-a-service (IaaS), platform-as-a-service (PaaS) and private/hybrid cloud have now reached $3.7 billion, with revenues for the past 12 months exceeding $13 billion.

The entire market is growing at a rate of more than 45 percent. Microsoft and IBM have both increased market share during the last four quarters, while AWS and Google are "essentially unchanged" from a year ago, Synergy Research said.

Billion Per Quarter

Amazon AWS takes in more than $1 billion per quarter, almost entirely from cloud infrastructure. While IBM and Microsoft also have quarterly revenue of about a billion dollars, its sources also include software/software-as-a-service, cloud-related hardware products and related services.

Synergy Research Group's Research Director John Dinsdale said in a statement that "it has become clear that AWS finally has some tough competition to face."

He noted that until this quarter, AWS "could claim it was bigger than its four nearest competitors, but now at least one jewel has fallen from its crown." Microsoft has been "making some huge strides in IaaS and PaaS," he said, "while IBM now has clear leadership in the private and hybrid infrastructure services segment."

In fact, the highlight of Microsoft's most recent quarterly earnings report was growth in its Azure cloud business. The company reported 147 percent in commercial cloud revenue, which would be an annualized run rate of over $4.4 billion. This did, however, include revenues from cloud-based Office365, Xbox and other services beyond computing, storage and network infrastructure.

Price Cuts

Amazon has been engaged in something of a price war with its competitors for months. In March, for instance, Google came out with substantial price cuts for its cloud computing businesses, with some cuts as steep as 85 percent. Amazon matched the cuts and Microsoft's Azure, which matches Amazon's prices as a policy, moved down as well.

Price cutting works to Amazon's favor when it involves, say, physical books that can be sold through the company's immense retail and distribution mechanism. This gives the retailer leverage against virtually every other retailer on the planet.

But in the cloud services business, Amazon not only has many of the same costs as its major competitors, but it has to match their price cuts to stay in competition.

Last week, Amazon's second quarter earnings report showed that its growth had slowed significantly compared to previous quarters.